Nextelbuddy

i now this is a vague question, but i am about to pull my block out and start putting my new pistons and rods in. right now i amtuned with hondata at stock compression. when i finish assembling my motor and u go to fire her up how will the motor run with the lowered compression on the current tune compared to the stock compression?

what i really am curious to know is since im lowering the compression i know that i will not make the same power @ 12 psi that i am making at stock compression with that said couldnt i just crank up t he boost lol?? i mean i shoudl have a less chance of detonation now since i am running lower compresion, then again i dont have any idea what im talking about.. i will get re tuned later, but what can i expect?

951

basically, from what i understand(not much, correct me if you have to)...less compression = less power from the same amount of boost. because the combustion chamber becomes bigger(volume-wise) as you lower the compression, thereby making each subsequent combustion a little less powerful. as you raise the CR however, the load/force exerted on your bottom end become greater and greater, im not sure if this increase is exponential, or direct...someone help.

Nextelbuddy

anyone else????

leadfoot78

You will not need as much fuel for low compression as high comp. but when u put a turbo into the equation it's a little more tricky. At idle it should be about the same, maybe it will sound a little different but thats probably from the new pistons. U should also check if u have the recommended, spark plug gap and base timing.

Nextelbuddy

any other input... thanx guys

Scott - 93HB Si

you will run richer and slower with the same program.

platinum00

dont lower your compression. keep it around stock.

car will be sluggish out of boost. , there is no need for lower compression with a good tuner.

platinum.

Nextelbuddy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by platinum00 &raquo;</TD></TR><TR><TD CLASS="quote">dont lower your compression. keep it around stock.

car will be sluggish out of boost. , there is no need for lower compression with a good tuner.

platinum.</TD></TR></TABLE>

what the hell are you talking about. im lowering compression anyways because im going with forged internals. no matter how good a tuner is stock internals are not good for high boost. i have already bought the 9:1 compression pistons so thats the end. your post was useless

jmagner

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by platinum00 &raquo;</TD></TR><TR><TD CLASS="quote">car will be sluggish out of boost. </TD></TR></TABLE>

I don't think so. Also, generally speaking, how often are you trying to be fast when your not boosting? The 9:1 will benefit boost. IMO, @ stock GSR compression, 12+ psi boost levels arent safe, especially for daily driving. btw thats my opinion.

leadfoot78

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nextelbuddy &raquo;</TD></TR><TR><TD CLASS="quote">

what the hell are you talking about. im lowering compression anyways because im going with forged internals. no matter how good a tuner is stock internals are not good for high boost. i have already bought the 9:1 compression pistons so thats the end. your post was useless</TD></TR></TABLE>

platinum is right, the motor will get more sluggish in low rpm, but 2 psi extra will more than make up the difference in high rpm, and like u said, it will be safer for your block to run forged 9.1 pistons. it's more preference than anything else I think, I'm going with the 9.1 forged pistons too, except they will be 84.5mm big with an LS crank so I'm not expecting my motor to be too sluggish.

platinum00

i was just stating that your car would be slower out of boost.

no where in you post did you mention you had already bought the pistons, or what compression you were running. i also never said keep your stock internals. forged is the only way to go. i did however say to keep the compression near stock

chill out a bit.

platinum.

jmagner

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by platinum00 &raquo;</TD></TR><TR><TD CLASS="quote">i was just stating that your car would be slower out of boost.</TD></TR></TABLE>

Yah I agree with this, I was bascily saying IMO it is a worthy trade-off.

Johnyquest

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nextelbuddy &raquo;</TD></TR><TR><TD CLASS="quote">

what the hell are you talking about. im lowering compression anyways because im going with forged internals. no matter how good a tuner is stock internals are not good for high boost. i have already bought the 9:1 compression pistons so thats the end. your post was useless</TD></TR></TABLE>

Don't be a dick. Your car will be slower out of boost. Lowering compression in my opinion is never a worthy tradeoff. I would have gone 10:1, but who gives a ****. It's too late now. Just tune the car, and then you tell us.

Good luck.
Matt

shermanyang

iTrader: (1)

lowering your compression is always a good idea. it puts a lot less stress on your motor, letting your turbo do some of the work. it's also a good safty precaution if and when you want to really turn up the boost, giving you more room to work with and for errors. you will be a bit slower out of boost but not noticieably slower. i'm running 8.5:1 in my ls right now and i really don't feel the difference between my car and my lil bro's stock LS with stock compression.


Just my .02